Many types of thermometers are known in the prior art. A popular type of thermometer is a cooking thermometer that includes a probe portion which is inserted in a food item being cooked in an oven. A cooking thermometer typically includes a dial or other visual readout that indicates how hot the food is. By observing the temperature of the food, and by monitoring the cooking time in the oven, it is assured that the food is properly cooked.
Most cooking thermometers include a body which encloses a chamber. The chamber houses an indicator that visually displays the temperature at the probe portion. The chamber is bounded by a glass pane through which the indicator is observed. A gasket is typically mounted under the glass pane to seal the chamber from the environment.
Cooking thermometers must be thoroughly cleaned between uses. This is done to remove food particles and avoid the growth of harmful bacteria. The most common way of washing a cooking thermometer is to place it in an automatic washer in which it is immersed in a hot water based cleaning solution.
Because of the different rates of thermal expansion of the glass pane and the typical metal body of the cooking thermometer, water vapor may infiltrate past the gasket into the chamber. When this occurs, water vapor is trapped inside the chamber upon cooling.
When a cooking thermometer with water trapped inside is placed in an oven, the water vapor will expand rapidly upon heating, causing pressure to build up in the chamber. Such pressure make cause damage to the seal; or, if the seal does not rupture, the glass pane may fracture. In either event, the thermometer becomes unusable.
Thus, there exists a need for a temperature sensing apparatus that may be used to sense temperature in a hot oven environment, but which will not be damaged by the infiltration of water vapor which may enter the body of the apparatus during cleaning.